The present invention relates to tool holders.
German patent document DE 196 21 610 A1 discloses a tool holder for a power tool, in particular for an electrical drill hammer. The drill hammer has a spindle sleeve, in which a base body of the tool holder is insertable and lockable by locking bodies. The locking bodies are releasably held in passages of the spindle sleeve by a spring ring and are radially overlapped by a securing body in a locking position. The spring ring which holds the locking bodies extends radially over a guiding surface of the spindle sleeve, on which the securing body is guided, and limits them in their axial movement.
For removing the tool holder, the securing body is displaced via an actuating sleeve axially to a position in which the locking bodies are radially released.
Accordingly, it is an object of the present invention to provide a tool holder of the above mentioned general type, which is a further improvement of the existing tool holders.
In accordance with the present invention a tool holder is provided for a hand power tool, in particular for a drill-and/or chisel hammer with a striking mechanism which drives a tool, and with a base body which is releasably mountable on a drive part through at least one locking body arranged in a throughgoing passage of a component and radially fixable in its engaging position by a securing body, which is guided by an actuating element for unlocking from its locking position to an unlocking position radially releasing the locking body, wherein the locking body is held by at least one holding element in the unlocking position of the securing body in the throughgoing passage.
It is proposed that the holding element is lowered or lowerable in the component which has the throughgoing passage and is overrun by the securing body. It is advantageous to provide a significant overlapping of the locking body by the securing body and thereby a particularly secure hold of the tool holder on the drive part. The holding element can be pressed by the securing body into a recess during overrunning or can advantageously be lowered completely in a recess, whereby friction between the holding element and the securing body can be avoided.
The holding element can be composed of various components which are suitable for the person skilled in the art, such as for example a pin and the like. It is advantageous when the holding element is formed as a spring ring arranged in a groove. Several locking bodies can be held by a spring ring in several throughgoing passages. In addition a spring ring is very simple and fast for mounting and dismounting.
For avoiding the situation that a gap of the holding element formed as a spring ring comes to abutment in the region of a locking body, it is advantageous to hold it by a rotation-securing ring in a peripheral direction. The rotation-securing ring can be also composed of components which are known for a person skilled in the art, for example of an additional beam which engages radially in the ring. It is especially advantageous when the rotation securing ring is formed as a hook provided on the holding element and a recess provided on the component which has the throughgoing passage. In the mounting condition of the holding element the hook engages in the recess. Additional components, mounting expenses and costs can be therefore avoided.
The securing ability of the spring ring is further increased and possibly a rotation-securing ring can be dispensed with when the spring ring has a gap which is smaller than the locking bodies. In conventional drill and chisel hammers the gap preferably is smaller than 3 mm.
Advantageously a holding element is arranged in an axial direction before and after the locking bodies, and therefore a tolerance, non sensitive secure hold can be provided. When each spring ring is provided with a rotary securing component, the spring rings advantageously can be held in positions which are turned relative to one another. The weak points of a spring ring because of a gap can be compensated by the other spring ring.
In accordance with a further embodiment of the present invention it is proposed that the securing body is limited in its movement in an axial direction opposite to the unlocking direction, by an abutment element arranged on the component having the throughgoing passage. With the abutment of the securing body against the abutment element the locking body is held in its engaging position via the securing body. The securing body is basically held opposite to the unlocking direction via the actuating element. When the actuating element is damaged so that the securing body no longer can be held, then the abutment element guarantees a required operation.
It is further proposed that the securing body can be displaceable by a corresponding component during displacement of the tool holder on the drive part to its unlocking position against a spring force of the spring element. The securing body can be also held releasably on the drive part and moved by the actuating element in a displacement direction of the tool holder against the spring force of a spring element to its unlocking position. The actuation of the actuating element for unlocking the securing body of the tool holder is oriented preferably opposite to an idle running pulse acting in the actuation direction. Thereby an automatic release is reliably prevented and in particular in high power drill and chisel hammers a secure mounting of the removable tool holder can be guaranteed.
The securing body can be deviated automatically to its unlocking position by the arrangement on the drive part preferably with mounting of the tool holder by a component on the tool holder. An unlocking movement of the securing body during automatic unlocking can be performed preferably in the same direction against the direction of the pressure spring during automatic unlocking for mounting of the tool holder on the drive part and an unlocking movement of the securing body during manual unlocking for release of the tool holder from the drive part.
The base body of the tool holder can include at least a part of the drive part in the mounted condition, and thereby a particularly robust and structurally simple design can be provided. A gap seal can be formed between an anvil of the striking mechanism and the drive part and protect a drive unit of the hand power tool from dirt. A reduced wear can be obtained and damages during insertion of the tool can be avoided. Furthermore, the locking bodies can be supported advantageously in the base body of the tool holder. Thereby the locking bodies when needed can be easily replaced or exchanged with the tool holder. Basically, the locking bodies can be held on the drive part.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.